A new short story! This is my first real shot at something humorous, so I hope I did a good job.

There are some notes at the end of the story, so make sure you check those out when you're done reading!

Please enjoy!

Disclaimer: I do not own Heroes of Olympus

Sibling Supremacy

Only one can be the Supreme Sibling. Post BoO, Humor

"Yeah, well I was born before you!"

"That doesn't count, you actually died!"

Being a summer camp (and for some, a year round camp) for demigods, Camp Half-Blood was no stranger to unusual things happening. Pegasus stampedes were common, satyrs seen every day, and there was the occasional monster. Not to mention the dragon that guarded the Golden Fleece. Dragons weren't uncommon either.

However, an event that was uncommon was the current occurrence between Nico di Angelo, and his sister Hazel Levesque. Since the war against Gaea, Nico had become a semi-permanent resident at Camp Half-Blood; as the only living child of Hades, Nico was head camper of the Hades cabin by default, but he still left camp to run errands for his father, and to avoid the resident head medic, Will Solace, whenever the overbearing son of Apollo thought Nico was 'overusing' his powers. Hazel on the other hand, was a permanent resident at Camp Jupiter, the demigod encampment located in San Francisco in a town named 'New Rome' for demigod children of the Roman aspect of the Gods. As such, Hazel was the daughter of Pluto, whose Greek form was Hades, Nico's father.

Surprisingly, Hazel and Nico got along very well for siblings, despite the fact that they were from two different pantheons, and by technical terms didn't share the same father. In fact, they got along so well, that they basically never argued, unless it had something to do with Nico's health.

Which was why what was occurring was so strange.

"Oh yeah? Well at least I didn't spend seventy years in a casino!" Hazel was shouting back to Nico at the top of her lungs when Jason graced the scene.

"What's going on?" He directed his question to Annabeth in the congregated group. Total, everyone watching the spectacle was Annabeth, Piper, Percy, and Frank.

"I'm not sure to be honest," Annabeth admitted, frowning slightly as two underworld children started shouting overtop of one another. "I just came over a few minutes ago."

"I think they're arguing about their age," Percy informed Jason, leaning over his girlfriend.

"Their age?" The idea was baffling to Jason. "Why are they arguing about that?"

"I've still been here longer!" The scene, also, was baffling to Jason. Both Nico and Hazel were red-faced, hands clenched in fists, and watching Nico childishly stamp his foot was a sight that Jason had thought he would never see.

"Apparently, it all started when Nico snuck out of the infirmary," Piper elaborated for her boyfriend.

"Again?" Jason was only mildly surprised at the news. It wasn't a secret that Nico didn't care for the infirmary that much, but whether it was because of the fact he was in the infirmary itself, or who always was his attending Apollo camper was left to debate. "What was he in there for this time?"

"Broken arm," Frank supplied, frowning. He looked as if he were debating whether or not to separate the siblings. "And then he passed out shortly after. Said it was just exhaustion, but…" He trailed off, furrowing his eyebrows together, deep in thought. "Anyway, he wasn't very happy when he woke up in the infirmary."

"So he snuck out." Jason finished, and the others nodded. "And Hazel got mad at him."

"Pretty much," Piper nodded. "Hazel then told him to 'act his age' and from there it devolved into what's going on now."

"Ah," Jason threw an arm around Piper's shoulder. "Who's winning?"

"I was completely aware of everything going around me in the Fields of Asphodel!" Hazel threw her arm out, pointing decisively at Nico. "You were unaware of everything going on around you in that dumb casino!"

"Yeah, well," Nico was floundering for why he was older, Jason could tell, and Nico finally settled on, "I'm thirteen! That's older than you!"

"I was thirteen when I died!" Hazel declared almost immediately, and right after an awkward silence fell upon their battleground. "Wait…"

"We're the…"

"Same age?!" Both Underworld kids adopted poses of disbelief, and it was Percy who had the brilliant idea to rekindle the argument by shouting,

"What month were you born?" He tossed in the suggestion casually, and Hazel and Nico fell upon it like two starving dogs on a bone.

"December!" Hazel answered, and Nico followed with an equally quick,

"January, hah!" He gave a sharp bark of laughter, before declaring triumphantly, "I'm older!"

"But wait," Frank cut in slowly. "Hazel, didn't you join the legion in September?"

"End of August, actually," Jason answered for him. "It was right before Juno did that 'exchange program' of hers."

"And it's August now," Annabeth said thoughtfully, "Which means…"

Hazel's eyes sparkled brightly like her birthday had come early.

"I'm actually fourteen!" It was Hazel's turn to shout victoriously. "Take that and eat it, Nico! I am the older sibling!"

"You're kidding me," Nico collapsed to his knees in defeat.

Hazel was laughing gleefully, clapping her hands together; Jason tried to think of a way to comfort Nico. It wasn't too bad, being the younger sibling. Not that he really had any experience being the younger sibling, that was.

Before anyone could do anything else, an enraged voice came from behind that had the group parting like a new opening in the Labyrinth.

"Patients who have not been discharged should not be out of the infirmary!"

It was Will Solace; head camper of the Apollo Cabin and the camper in charge of the infirmary. He befell upon the group in a similar manner to one of their parents when they were enraged. Light from the sun behind him illuminated his figure, making his blue eyes seem sharper, and made the freckles on his tanned face more pronounced. There was a stethoscope hanging around his neck, and a clipboard under his arm. Will's face was contorted in anger, an emotion that Jason rarely saw on his face.

"All of you, back to the infirmary!" Will ordered, a no-nonsense tone to his voice. "And you, di Angelo, you were due for a check-up two hours ago! Get back to your bed, now!"

"Make me!" Nico snapped back, standing up.

A sort of stunned silence fell over the group, quiet enough to hear a pin drop.

"What did you say?" Will's voice was low and quiet, but exuded an aura that made everyone but Nico take a subtle step away from the Apollo camper.

"Are you going deaf?" Nico retorted crossly, "I said make me!"

"As Head Medic, I'm not going to put up with this di Angelo!"

"What're you gonna do, put a curse on me?" Nico snubbed Will. "Make me speak in limericks? Well bring it on! I'm not afraid of you!"

"Y-You can't speak to me that way, di Angelo!" Will sputtered, face flushing red.

"Aw, young love," Piper sighed laughingly, whispering mostly to Jason.

"Love?" Jason looked at his girlfriend, startled. "Those two? No way."

"Believe me," Piper rolled her eyes teasingly, "If there's anyone who knows love, it's a child of Aphrodite. There's definitely something there between them."

"If you say so…" Jason muttered doubtfully, before Piper tugged on his arm.

"I do say so," She agreed. "Now let's go, while Will is distracted."

"Wait," Jason yelped as Piper dragged him along with an unbelievably strong grip, stumbling over his feet, noticing for the first time that everyone else aside from them and Nico and Will had absconded. "Why are we running from Will?"

"Don't worry," Piper laughed, beaming, as they made for the woods by the lake for their hiding spot. "I'll tell you later!"

So what spawned this story is the fact that people always say that between Nico and Hazel, Nico's the older sibling when he's not. Nico was 10 when he was first introduced in The Titan's Curse. 11 in Battle of the Labyrinth, and 12 during The Last Olympian. The sequel series starts immediately after TLO, with The Lost Hero starting late-September/a month or two after TLO. Nico's still 12 at this point; by the start of The Son of Neptune, which starts in May, Nico's arguably has already has his 13th birthday, depending if you go with his birthday being in January, or with it's placement in May. For the rest of the series, straight through Blood of Olympus, Nico is 13.

As for Hazel, during one of her flashbacks in Son of Neptune, we find out that she first meets Pluto, her father, on her 13th birthday- he gives her a pack of colored pencils, and Hazel makes a sort of snubbing comment wondering if it would be another 13 years before she saw her father again. She and her mom go to Alaska, and she dies before her 14th birthday. But, as we find out, Hazel joined the Legion sometime around August/September, before the Lost Hero, presumably. This is a bit up in the air between the two months, because even there's a bit of disagreement between books, because in one book Hazel says that she met Jason briefly before he disappeared (he vouched for her to stay) but in another it says that Hazel hadn't seen Jason before? Either way, she joined in August-September after TLO, and when we're first introduced in SoN, it's may, so technically her birthday's already passed and she's 14.

Still, even if you want to argue and say she's not older than Nico because she's been dead and a year hasn't passed, she doesn't consider herself 14, etc, etc, you'd still be off, because then they'd both be 13, and Hazel would still be older, because her 14th birthday would come first in December before Nico's 14th birthday in January seeing as he just turned 13 the January before Son of Neptune. Either way, Hazel is still the older sibling.